Yongshik ParkFebruary 13th, 2008EE C235/NSE C203

Scanning Probe Lithography

OutlineScanned Probe Oxidation

Generating an Polymer “Resist” Layer using

Scanning Probe Lithography

High-Field Scanning Probe Lithography in

Hexadecane

Cons and Pros

Conclusions

Scanned Probe Oxidation

Began at NIST in 1989Electrical bias between a conducting tip

and a substrate induces a highly localized enhanced oxidation.

Typical line width: 10~20nm

J. A. Dagata, Science, Vol. 270, 1995, pp1625-1626

Scanned Probe Oxidation- Applications

Fabrication of Si nanowire Fabrication of single tunneling transistor(SET)

J. A. Dagata, Science, Vol. 270, 1995, pp1625-1626

Generating an Etch Resistant “Resist” Layer from Common Solvents

An organic electrolyte replaces water to generate an organic resist.

Scan rate: 10um~20um

DC Bias

Fluid Cell

Solvent vapor

I. Suez, S. Backer, J. Frechet, Nano Letter, Vol. 5, No. 2, 2005, pp321-324

Generating an Etch Resistant “Resist” Layer from Common Solvents

The height of n-octane: 2.5nm (40% higher than the case of water)

After etching, the height of step: 8.5nm

After generating n-octane patterns After etching

I. Suez, S. Backer, J. Frechet, Nano Letter, Vol. 5, No. 2, 2005, pp321-324

High-Field Scanning Probe Lithography in Hexadecane - Hydrophobocity

Surface hydrophobocity

determines the deposited material.

Hydrophilic SiO2

Hydrophobic n-octane

Oxidation of the silicon surface

occurs in the meniscus formed by

the water dissolved in the fluid,

with minimal effects on the

reaction from the surrounding

solvents

I. Suez, M. Rolandi, S. Backer, A. Scholl, J. Frechet, Advanced Materials, Vol. 19, 2007, pp3570-3573

High-Field Scanning Probe Lithography in Hexadecane - Hydrophobocity

Etching makes trenches on hydrophilic surface and tall posts on hydrophobic surface.

On Hydrophilic surface On Hydrophobic surface

After deposition(black)

After etching(red)

I. Suez, M. Rolandi, S. Backer, A. Scholl, J. Frechet, Advanced Materials, Vol. 19, 2007, pp3570-3573

High-Field Scanning Probe Lithography in Hexadecane – PEEM analysis

Although there are only small differences in features of the local spectra, carbon content information was obtained1st and 2nd peak: C=C double bond3rd peak: hybridized carbon atoms

I. Suez, M. Rolandi, S. Backer, A. Scholl, J. Frechet, Advanced Materials, Vol. 19, 2007, pp3570-3573

PEEM analysisAFM image Carbon signal PEEM

Cons and ProsCons

Can make nano patterns without optical apparatus

Can control deposited material by hydrophobocity of the surface

Can make arbitrary patterns by controlling the trajectory of AFM tip

ProsLow throughput: serial scan and low speed

Multiple tipsSmall scan area

ConclusionsScanning probe oxidation can make

nanowire, SET, etc.By using an organic solvent, the organic

material can be deposited on the surface.The hydrophobocity determines the

deposited materialHydrophilic surface SiO2Hydrophobic surface hydrocarbon

By PEEM analysis, the deposited material on the hydrophobic surface has carbon components.